Synovial Fluid Analysis

Written by Amber Gabbey | Published on July 25, 2012
Medically Reviewed by Brenda B. Spriggs, MD, MPH, FACP

Overview

Each of the joints in the human body contains synovial fluid. This fluid is a thick liquid that lubricates the joint and allows for ease of movement. The synovium of the joint is the main place where inflammation occurs in joint diseases such as arthritis. The first sign of joint disorders is often limited mobility in the joint or pain and stiffness with movement. Cases of synovial fluid and joint inflammation are more common with increased age.

Synovial fluid analysis is also known as joint fluid analysis.

When is the Test Done

A synovial fluid analysis is performed when there is pain, inflammation, or swelling in a joint or when there is an accumulation of fluid. Taking a sample of the fluid can help diagnose the exact problem that is causing the inflammation.

Some potential diagnoses include infection, gout, arthritis, and bleeding. In some cases when there is excess fluid, simply removing some fluid helps to relieve pain in the affected joint. Sometimes synovial fluid analysis is used to monitor people with known joint disorders.

What to Expect

A synovial fluid analysis may be mildly uncomfortable, but the whole process lasts only a few minutes. You might receive a local anesthesia to numb the area. You may feel a prick and burning sensation from the anesthesia at the site of entry.

A larger needle will then be inserted into the joint to withdraw the synovial fluid. If you received anesthesia, you should feel minimal discomfort. If you did not receive anesthesia, the needle may cause slight pain and discomfort. You might feel pain if the tip of the needle touches bone or a nerve. Following the procedure, apply ice to reduce any pain or swelling.

Synovial Fluid Analysis Process

Your healthcare provider will recommend a synovial fluid analysis if you have signs of joint inflammation, redness, swelling, or injury. The test can help diagnose the condition. You will not need to do anything in preparation for the test, but be sure to notify your healthcare provider if you are taking blood thinners, as they can affect the testing.

The synovial biopsy process will be done at your physician’s office. This process does not require any incisions and will only take a couple of minutes. First, the area will be cleaned and prepared for injections. If you are getting anesthesia, it will be injected into the site to limit pain and discomfort. Once the area has been numbed, a larger needle will be inserted into the joint and draw fluid out into the syringe. This process of removing fluid from a joint is called arthrocentesis.

The fluid sample will then be sent to the laboratory for examination. The technician will first look at the color and thickness of the fluid. He or she will then assess red and white blood cells under a microscope. The technician will also look for crystals or signs of bacteria and measure glucose, proteins, uric acid, and lactic dehydrogenase, an enzyme seen in increased amounts in cases of inflammtion and tissue damage. Finally, the fluid sample will be cultured to test for bacteria.

What Do the Test Results Mean?

Normal synovial fluid is straw-colored, clear, and slightly sticky or stringy.

Abnormal synovial fluid will be cloudy or thicker than normal fluid.

Cloudiness could mean there are crystals, increased white blood cells, or microorganisms in the fluid. In the case of gout, the fluid will contain crystals. Less stringiness in the fluid could signal inflammation. Excess fluid in the joint could be a predictor of osteoarthritis. Reddish-colored fluid could mean blood is present. Blood found in the fluid could point to a bleeding injury in the joint or a more serious bleeding problem throughout the body, such as undiagnosed hemophilia, a bleeding disorder due to absent or ineffective clotting factors.

Cloudy fluid, blood in the fluid, or excess fluid are all signs that there is a problem in or around the joint, such as gout, arthritis, infection, autoimmune disorders, or an injury to the joint. This procedure has been found to be highly effective in diagnosing gout through the identification of crystals in the fluid.

The Risks of Synovial Fluid Analysis

There are minimal risks associated with a synovial fluid test. The most common risks are bleeding or infection in the joint. More commonly, you may experience soreness or stiffness in the joint. Complications from this procedure are rare.

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